Recent efforts involve further characterization of the biological and molecular features of Mycoplasma genitalium, in anticipation that this information will lead to development of improved methods in detection of the organism and more definite confirmation of its role in human urogenital disease. The identification of a unique attachment (surface) protein (molecular wt. 140 kDa) on the organism differentiates it clearly from other pathogenic mycoplasmas with organized terminal structures and identifiable attachment proteins. Cross-reactive as well as species-specific protein of M. genitalium and M. pneumoniae have been identified using monoclonal antibodies generated against these mycoplasmas in ELISA and Western blot analyses. An immuno-binding test, using mycoplasma blotted onto nictrocellulose paper and monoclonal or polyclonal antibody preparations to M. genitalium as an immunologic probe for detection of the organism, proved specific but with inadequate sensitivity for use as a practical diagnostic test. In collaboration with investigators in Israel and LMM, a radiolabeled DNA probe can detect 0.1 nanogram of M. genitalium DNA and approximately 1000 organisms, and does not hybridize with other mycoplasmas found in the human urogenital tract. In other work, biological and molecular features of a large group of mollicutes (wall-less prokaryotes) were examined for their potential in genetic transformation studies. A plasmid (pRA1) obtained from spiroplasma in this group has been shown to possess short, interspersed, and repetitive DNA sequences that are also found to hybridize to chromosomal DNA form three plant pathogenic spiroplasmas. It was also demonstrated that these same DNA fragments exhibited homology to DNA obtained from certain type 3 spiroplasma viruses. The biologic function of these common sequences among spiroplasma chromosomes, plasmid and viruses is not presently understood.